Question

find the rate of compound interest p.a at which rs 25000 will amount to rs 43200 in 3 years compounded annually.

Answer 1

A=p(1+r/100)
43200=25000(1+r/100)
43200=250×(100+r)
100+r=43200/250
r=(43200/250)-100
r=(43200-25000)/100
r=182/100

Answer 2

Given :

Principal = Rs.25000

Amount = Rs.43200

Time = 3 years

To Find :

Rate of interest

Solution:

Principal = Rs.25000

Amount = Rs.43200

Time = 3 years

Formula :

$A=P(1+r)^t$

Substitute the values :

$43200=25000(1+r)^3\\\frac{43200}{25000}=(1+r)^3\\\sqrt[3]{\frac{43200}{25000}}=1+r\\\sqrt[3]{\frac{43200}{25000}}-1=r$

0.2 = r

r=20%

Hence The rate of interest is 20%